1. Field
The field relates to a power converter, and a switching controller and a driving method thereof.
2. Description of the Related Art
A power converter, for example a switching mode power supply (SMPS), rectifies an input alternating current (AC) voltage to generate an input direct current (DC) voltage, and converts the input DC voltage to an output voltage having a different level from the input DC voltage. The power converter is used for a power supply of an electronic device, for example a cellular telephone, a computer, or a television.
An operation mode of the electronic device includes a normal operation mode and a standby operation mode. The electronic device consumes a large amount of power in the normal operation mode, as compared to the standby operation mode.
Generally, the power converter provides a burst mode in which an operation for turning off a switch of a primary side of a transformer included in the power converter after turning on the switch during a predetermined time in accordance with a feedback voltage is repeated. The power converter generates the output voltage that is required in the standby operation mode during a burst mode such that the electronic device can reduce power consumption in the standby operation mode.
The power converter may have a threshold range between a high threshold voltage and a low threshold voltage for the burst mode, and the feedback voltage of the power converter may be inversely proportional to the output voltage of the power converter. In this case, in the burst mode, the power converter turns on the switch when the feedback voltage is higher than the high threshold voltage, and turns off the switch when the feedback voltage is lower than the low threshold voltage.
A current, which flows to the switch when the feedback voltage reaches the high threshold voltage at a starting time of the burst mode, has the highest magnitude among currents flowing to the switch in the burst mode. That is, a large amount of current may flow to the switch at the starting time of the burst mode. Parasitic mechanical vibrations can occur in the power converter by the large amount of current flowing to the switch such that an audible noise can be caused.